There has been an erasing apparatus for color erasing (decolorizing) an image on a sheet. The erasing apparatus includes a color erasing device (decolorizing section) which performs a heating treatment on a sheet with a printed image so as to color erase (decolorize) the image (color material) on the sheet.
The color erasing device heats the sheet up to a predetermined temperature (decolorization temperature) so as to color erase the image. In order to reuse such a sheet, it is desired to reduce, as much as possible, a non color erased (non-decolorized) portion of the image left after the color erasing process thereto.